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"""Small but quite comprehensive example showing the use of PyTables.
The program creates an output file, 'tutorial1.h5'. You can view it
with any HDF5 generic utility.
"""
import numpy as np
import tables as tb
# '-**-**-**-**-**-**- user record definition -**-**-**-**-**-**-**-'
# Define a user record to characterize some kind of particles
class Particle(tb.IsDescription):
name = tb.StringCol(16) # 16-character String
idnumber = tb.Int64Col() # Signed 64-bit integer
ADCcount = tb.UInt16Col() # Unsigned short integer
TDCcount = tb.UInt8Col() # unsigned byte
grid_i = tb.Int32Col() # integer
grid_j = tb.Int32Col() # integer
pressure = tb.Float32Col() # float (single-precision)
energy = tb.Float64Col() # double (double-precision)
print()
print("-**-**-**-**-**-**- file creation -**-**-**-**-**-**-**-")
# The name of our HDF5 filename
filename = "tutorial1.h5"
print("Creating file:", filename)
# Open a file in "w"rite mode
h5file = tb.open_file(filename, mode="w", title="Test file")
print()
print("-**-**-**-**-**- group and table creation -**-**-**-**-**-**-**-")
# Create a new group under "/" (root)
group = h5file.create_group("/", "detector", "Detector information")
print("Group '/detector' created")
# Create one table on it
table = h5file.create_table(group, "readout", Particle, "Readout example")
print("Table '/detector/readout' created")
# Print the file
print(h5file)
print()
print(repr(h5file))
# Get a shortcut to the record object in table
particle = table.row
# Fill the table with 10 particles
for i in range(10):
particle["name"] = "Particle: %6d" % (i)
particle["TDCcount"] = i % 256
particle["ADCcount"] = (i * 256) % (1 << 16)
particle["grid_i"] = i
particle["grid_j"] = 10 - i
particle["pressure"] = float(i * i)
particle["energy"] = float(particle["pressure"] ** 4)
particle["idnumber"] = i * (2**34)
particle.append()
# Flush the buffers for table
table.flush()
print()
print("-**-**-**-**-**-**- table data reading & selection -**-**-**-**-**-")
# Read actual data from table. We are interested in collecting pressure values
# on entries where TDCcount field is greater than 3 and pressure less than 50
xs = [
x
for x in table.iterrows()
if x["TDCcount"] > 3 and 20 <= x["pressure"] < 50
]
pressure = [x["pressure"] for x in xs]
print("Last record read:")
print(repr(xs[-1]))
print("Field pressure elements satisfying the cuts:")
print(repr(pressure))
# Read also the names with the same cuts
names = [
x["name"]
for x in table.where(
"""(TDCcount > 3) & (20 <= pressure) & (pressure < 50)"""
)
]
print("Field names elements satisfying the cuts:")
print(repr(names))
print()
print("-**-**-**-**-**-**- array object creation -**-**-**-**-**-**-**-")
print("Creating a new group called '/columns' to hold new arrays")
gcolumns = h5file.create_group(h5file.root, "columns", "Pressure and Name")
print("Creating an array called 'pressure' under '/columns' group")
h5file.create_array(
gcolumns, "pressure", np.array(pressure), "Pressure column selection"
)
print(repr(h5file.root.columns.pressure))
print("Creating another array called 'name' under '/columns' group")
h5file.create_array(gcolumns, "name", names, "Name column selection")
print(repr(h5file.root.columns.name))
print("HDF5 file:")
print(h5file)
# Close the file
h5file.close()
print("File '" + filename + "' created")
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